This invention relates to meat processing. More particularly, the invention relates to a method for adding ammonia to a comminuted meat product to produce a pH enhanced comminuted meat product.
Almost all foods are processed in some way before reaching the consumer. Meat products, for example, are separated from unusable or undesirable elements or components, ground or chopped, mixed or blended, and often times frozen for distribution. Even lightly processed meats are cut, trimmed, and then packaged for sale or distribution.
Microbes are part of the natural decay process of organic material and invariably appear or grow in foodstuffs as they are processed or handled. Although some microbes may be relatively benign, others contribute to spoilage and some can cause serious illness if consumed. Lactic acid producing bacteria are examples of benign microbes while some strains of E. Coli, Salmonella, Staph, and Listeria bacteria are examples of pathogens and can cause serious illness.
It is desirable to control the growth of pathogen microbes or reduce pathogen microbe count in foodstuffs. Historically, microbe growth has been reduced by chemical preservatives that remain in the product and are ultimately ingested by the consumer. However, a growing population of consumers has expressed a desire for food products that are free of traditional chemical preservatives. Alternatively to traditional chemical preservatives, heat has been used to kill microbes in foodstuffs. However, heat processing or sterilization often has an undesirable effect on the quality or characteristics of the foodstuff and may make the product undesirable to the consumer. Also, heat sterilization in meats can kill all microbes, leaving the meat susceptible to the rapid growth of dangerous microbes or pathogens after sterilization, should the previously sterilized meat be exposed to such microbes.
The prior related application Ser. No. 09/213,190, now U.S. Pat. No. 6,389,838 B1 discloses an apparatus and method for physically manipulating a pH modified comminuted meat product to reduce the microbe content in the resulting product. The process includes freezing the pH modified meat product and then physically manipulating the frozen material to produce relative movement between points within the material. This process of treating a pH modified meat product, which may be referred to as xe2x80x9cfreeze/stress processing,xe2x80x9d has been found to greatly reduce the live microbe count in the resulting product.
It is a general object of the invention to provide a method for producing a pH enhanced comminuted meat product. The pH enhanced comminuted meat product produced according to the invention is well suited for use in freeze/stress processing to dramatically reduce live microbe content in the resulting product.
The method of producing a pH enhanced comminuted meat product according to the invention includes placing ammonia in contact with an initial comminuted meat product. This contact with ammonia results in an intermediate meat product having a pH higher than the initial comminuted meat product. Once the intermediate meat product is produced, the method includes releasing or removing ammonia from the surface of the intermediate meat product and then applying mechanical action to the intermediate meat product. This mechanical action helps drive ammonia deposited on the intermediate meat product into the meat and helps distribute the ammonia in the meat product. Removing ammonia from the surface of the intermediate meat helps ensure that the mechanical action does not cause too much ammonia to be absorbed into the intermediate meat product, and produce an overly ammoniated product.
One preferred form of the invention applies ammonia in the form of a gas at relatively high pressures. Using high pressure ammonia gas allows the ammonia gas pressure to be held for only a very short operating period, on the order of seconds or fractions of a second, and still raise the pH at the surface of the meat product to a desired level.
As used in this disclosure and the following claims, the xe2x80x9csurfacexe2x80x9d of the meat product means generally any surface that may be exposed to the ammonia. For example, the surface of ground meat may include the entire surface of each piece of ground meat and not just the surface of the aggregate made up of individual ground pieces.
While the preferred forms of the present invention apply ammonia in the form of a gas, it will be appreciated that the ammonia may be applied in solution with water within the scope of the invention. It is believed that the ammonia gas goes into solution in water in the initial meat product to form an ammonium hydroxide solution generally at the surface of the intermediate meat product. Where ammonia is added in the form of an ammonium hydroxide solution, it is believed that the ammonium hydroxide solution simply mixes with the water in the initial meat product to produce the desired intermediate meat product.
The method of the invention may be performed as a continuous process with an apparatus such as that disclosed in U.S. Pat. No. 5,433,142 or as a batch process. In either case, the apparatus for performing the process includes a container for containing the initial meat product and ammonia and also means for placing the initial meat product and ammonia in the container and for removing the intermediate meat product from the container after treatment. The continuous process apparatus also preferably includes means for compressing ammonia gas in contact with the meat product to the operating pressure and means for releasing the pressure after the operating period. In the batch process, the meat product may be held in a pressure vessel and ammonia gas may be introduced into the vessel under the desired operating pressure.
The ammonia releasing or removing step serves to remove any excess or free ammonia from the intermediate meat product. In one form of the invention, the ammonia releasing or removing step may include rinsing the surface of the intermediate meat product with a suitable inert gas or a liquid. In another preferred form of the invention, the ammonia releasing or removing step includes placing the previously treated meat under a vacuum to draw off excess ammonia gas from the intermediate product. In addition to applying a vacuum to the treated product, the temperature of the intermediate product may be increased to help release ammonia gas from the product. The intermediate meat product may also be agitated or blended while applying a vacuum.
The mechanical action according to the invention may be applied in a number of different fashions. The agitation or blending while removing ammonia from the surface of the intermediate meat product may be referred to as a primary mechanical action. Pumping the intermediate meat product through a conduit also applies the desired mechanical action to the intermediate meat product. An initial mechanical action by pumping the intermediate meat product may be applied prior to the primary mechanical action. A secondary mechanical action by pumping the intermediate meat product may be applied after the primary mechanical action.
These and other objects, advantages, and features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.